Dark triad personalities — narcissism, Machiavellianism, and psychopathy — rely on manipulating other people as their source of power. They thrive off creating chaos for everyone around them, under the illusion of being a caring partner or friend.

When you mention psychopaths, many people will imagine a murderer, rapist, or Hannibal Lecter type. The reality is a lot less dramatic. Someone doesn't have to have committed a violent crime to be diagnosed as a psychopath, and taking a lot of selfies doesn't make someone a narcissist.

They still cause harm to others, but it's more likely to be the emotional and psychological harm that doesn't leave physical scars. That's why they can hop from partner to partner without leaving much of a trace of their destruction.

Doctor of psychology and therapist Perpetua Neo spoke with Business Insider about how dark triad people slip through the cracks, and how our misconceptions can help them manipulate others.

Here are 10 reasons dark triad people are so difficult to spot:

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1. They are not all Jack the Ripper

Relatively few psychopaths have a taste for blood. Neo said we tend to believe most psychopaths are in prison, because they are cold-blooded murderers, rapists, or paedophiles, but this simply isn't true for most of them.

She said we tend to ask ourselves if someone is a full-blown psychopath, such as Jack the Ripper, which means we ignore the other signs that they are probably on the spectrum.

"It's just a way we use to justify it to ourselves that there is a good person inside this person, or maybe I'm just bringing the bad side out of this person," she said. "I think the question should be 'are they good to you and are they good for you?'

"Do you really need a person to be Jack the Ripper before you decide to disengage from them?"

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2. Their job proves nothing

If someone is respected in the community, it is harder to assume their intentions aren't good. But sometimes, dark triad people will go into professions that will mask their true intentions. Neo said this always makes her think of the Catholic church, and when they tried to cover up the abuse of young children.

"Because somebody is in a position in a community, we think they're a good person," she said. "Just like if someone's a psychologist or therapist, we think they're a good person. But having gifts doesn't make you a good person. We just conflate all these ideas in our head. Which means for instance, a psychopath may choose to work in a charity, in the third sector, so they can look like they're very giving people. That's how they worm their way in."

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3. They can actually show empathy

Dark triad people are more or less devoid of empathy. But Neo said there are two types of empathy — cognitive and affective. Affective empathy is when you truly feel something for someone else, whereas cognitive empathy is the ability to recognise the feelings in others.

Narcissists and psychopaths often watch a lot of TV and films, so they are able to develop cognitive empathy and mimic the behaviours that are appropriate in those situations. For example, they may know to give you a hug, but there is no feeling behind it — they're just copying what they've learned.

"They can seem empathetic even if they lack empathy," Neo said. "But it's their everyday behaviour, what kind of contempt leaks out, that matters. If they seem empathetic towards a person, then the next thing you hear might be a strange remark, or a weird sick joke, then you know this person doesn't really have empathy."

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4. They can be excessively charming

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Dark triad people can turn on the charm in a matter of seconds. You may be having an argument, and they can switch it on and act like a completely different person.

Neo said when you meet someone and they are too charming, it could be because they are trying to hook you in with love bombing. It's an effective — and highly manipulative — method of making you feel like you've found your soulmate, and it often starts with the person being highly affectionate, charming, and generous.

"If it doesn't feel natural, you get goosebumps, or feel off kilter, that's a sign," she said. "We know that excessive levels of charm correlate with dark triad traits... but our bodies and brains are wired to react in a way that gets hooked on to them instead."

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5. They do their homework on you

Although dark triad people are very good at making you feel like meeting them was fate, this probably isn't true. While they are love bombing you, and telling you how you're "the one," they may have orchestrated the whole relationship.

Neo said it's not uncommon for a narcissist to stalk their potential targets. She heard of one narcissistic man who stalked his wife for three years before they met.

"It's normal to maybe look someone up on Facebook before you meet them," she said. "But these people... they get sophisticated and they play the long game."

It's a common trap narcissists set for their victims, she said. They learn everything they possibly can about you, then instrument a way to meet you. Then they act as if you have so much in common because you must be "soulmates."

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6. They tell you how much you mean to them

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Dark triad people have had a lot of practise hooking people in then discarding them when they are no longer of any use to them, so they know exactly what to say to keep you interested.

No matter how many times they abuse and let them down, their partner always wants to see the good in them. Neo said this is down to confirmation bias, and discounting any evidence that doesn't align with our beliefs. In the case of dark triad partners, this belief is that they are actually good people underneath.

"They also like to use words like 'I really care about you,' or 'I really support you,' or even 'I love you,'" Neo said. "If someone says these words, you want to believe he supports you. You will take these words, and you will discount all the times he's an a*****e. That's how the brain works, and they know that."

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7. It's never all bad

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No relationship is ever going to be 100% awful. Even the most abusive and turbulent relationships have their good times, which is one of the main reasons people stay with the people who hurt them for so long.

Some people get trauma bonded to their partners, which means they are essentially chemically addicted to the intermittent love and affection they get when things are good. They also strive to get the good times back when things are really awful, because they are led to believe all the negatives in the relationship are their own fault.

"If it was all bad, it would be easy to dismiss them and walk away," Neo said. "But because there are good times... you see this flicker of humanity in them and you want to harness that."

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8. They have sob stories

If you meet a narcissist, they will probably let you know how much of a hard life they've had fairly early on. Everyone goes through tough times, but according to Neo, narcissists take it to the extreme.

They will probably tell you about their abusive upbringing, their abusive ex-partners, and how their friends are awful to them. But if you listen closely, they are likely to be blaming other people for their own behaviours — that's if the stories are true at all.

"We believe that this person has a sad sob story, that it's not their fault," Neo said. "Ultimately it doesn't matter how they were made. Yes, it's sad someone has that background that shaped them in a certain way, but the big question is 'are they good to you?'"

If not, it's time to let them go.

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9. They go after highly empathetic people

Somebody high in empathy is highly in tune with other people's emotions, and will constantly try and help out someone who they think is hurting. Unfortunately, narcissists thrive on this level of care, and use it to destroy their partner.

They know they have a partner who will love them selflessly, give them as much attention as they need, and won't be as quick as other people to walk away.

"Empathetic people will be very long suffering if a narcissist says 'I really want to change, I know I'm not perfect.'" said Shannon Thomas, a therapist, in a previous article. "They have these moments where they sort of admit fault, but they never actually follow through or believe it."

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10. They gaslight you

Manipulative people, who are often dark triad personalities, gaslight their partners into believing in an alternative reality. This is when someone "screws with your sense of reality to manipulate you, causing you to distrust yourself and trust them instead," Neo said.

Narcissists, for example, may constantly lie to their victim. It starts off with a subtle untruth here and there, so the victim doesn't realise they're being brainwashed.

It's like the "frog in the saucepan" analogy: where the heat is turned up very slowly on the stove, so the frog never realises it's starting to boil to death.